Switch off the lamp in imported VRML
You could try uncommenting the is_on line and add something like

bpylamp.hide = not is_on
bpylamp.hide_render = not is_on


Another option could be

if is_on:
    bpylamp.energy = intensity
else:
    bpylamp.energy = 0


The X3D/VRML2 import script was written by Campbell and Bart so you might want to contact them and ask what they planned to do with the lights and whether they want some help. It's possible they left it like that because there is no on/off light switch in blender (maybe adding one is a TODO somewhere).